Equilibrium and rate constants for the following types of protonic reactions are being obtained in the gas phase utilizing ion cyclotron resonance spectroscopy: A1H plus A2 yields reversibly A2H ion plus A1. A1H ion..B plus A2 yields reversibly A2H ion B plus A1, AH ion B1 plus B2 yields reversibly AH ion..B2 plus B1. The work involves basic molecules, i.e., A, A1, A2, B, B1, B2, which contain functional groups of biological importance. Emphasis is placed upon conjugate acids of pyridine derivatives as well as cations of the OH ion, NH ion, SH ion, and PH ion types. It is proposed to develop a "solvent" molecule which models quantitatively in the gas phase certain roles of the aqueous medium. Hydrogen-bond affinities of bases for gaseous cationic proton donors will be compared with pKHB parameters for a critical series of bases. F-nmr shielding parameters for appropriately substituted fluorobenzenes are being utilized in sensitive studies of hydrogen bonding of ionic substituents with solvents. A quantitative model for hydrogen-bonding medium effects has been proposed. Critical tests of the treatment are being made. BIBLIOGRAPHIC REFERENCES: E. M. Arnett, B. Chawla, L. Bell, M. Taagepera, W. J. Hehre, and R. W. Taft, "Solvation and Hydrogen-Bonding of Pyridinium Ions," J. Amer. Chem. Soc., 99, 0000 (1977). J. F. Wolf, J. M. Abboud, and R. W. Taft, "Regarding Polarizability Effects of Hydrocarbon Substituents on Base Strengths in Solution," J. Org. Chem., 42, 0000 (1977).